sfc: stop the TX queue before pushing new buffers

sfc: stop the TX queue before pushing new buffers

BugLink: https://bugs.launchpad.net/bugs/1836635
efx_enqueue_skb() can push new buffers for the xmit_more functionality.
We must stops the TX queue before this or else the TX queue does not get
restarted and we get a netdev watchdog.

In the error handling we may now need to unwind more than 1 packet, and
we may need to push the new buffers onto the partner queue.

v2: In the error leg also push this queue if xmit_more is set

Fixes: e9117e5099ea ("sfc: Firmware-Assisted TSO version 2")
Reported-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Martin Habets <mhabets@solarflare.com>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 0c235113b3c42197dba66baf76697359b03a5046)
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>